This is my first trailer, I was inspired by several trailers found on Instructables, picking the best from all of them. I used a corner Aluminium profile, 40x40mm width (1,57 in) and 2mm thick (0,07 in) totally about 8 meters, a square aluminium pipe (40mm width), iron square pipe (30x30mm), tropicalized brackets, rivets, some bolts and nuts. Then I needed 2 16'' front bike wheels, beads (no matter the thickness), screws.
I had to buy more aluminium than needed but the total cost with right quantities is about 50-70 Euro.
as a test, 80 kg, about 175 pounds were smoothly transported.
Step 1: What is needed
2 x 16'' bike front wheels
4 x 1mt aluminium corner profile - 2 of them with sides cuts at 45°
4 x 80cm aluminium corner profile - 2 of them with sides cuts at 45°
1 x aluminium square pipe (40mm wide)
10 x tropicalized brackets (4 flat 90°, 4 vertical 90°, 2 linear
4 x corner brackets
about 2m of iron square pipe 30mm wide (that replaced the round pipe in the image that was not working good)
beads (I used the 2cm thick ones)
rivets, screws, bolts and nuts
hand made gimbal